Zoom lens and imaging device

Abstract

[Problem] To obtain high optical performance over an entire zoom range and at all distances to objects while acheiving a reduced weight of a focus group. [Solution] A zoom lens L0 comprises a positive first lens group L1, a negative second lens group L2, and a plurality of subsequent lens groups. The first lens group does not move during zooming, and the second lens group moves during zooming. The plurality of subsequent lens groups include a first focus group Lfc1 and a second focus group Lfc2 that move during zooming and focusing. A focal length ff1 of the first focus group, a focal length ff2 of the second focus group, a distance TTL to an image surface from the object-side surface of a first lens closest to the object side of the zoom lens when focused at infinity at a wide-angle end, and a distance Lff1w to the image surface from the image-side surface of the lens closest to the image side in the first focus group when focused at infinity at the wide-angle end satisfy the conditions 0 < |ff2 / ff1| ≤ 0.95 and 0.45 ≤ Lff1w / TTL ≤ 0.80.

Description

Zoom lens and imaging device

[0001] The present invention relates to a zoom lens suitable for imaging.

[0002] Zoom lenses are required to have high optical performance over the entire object distance range from infinity to the closest point, while also achieving quiet and high-speed focusing.

[0003] Japanese Patent Application Laid-Open No. 2006-129999 discloses a zoom lens in which a focus group that moves during focusing is located within the first lens group closest to the object. In this zoom lens, spherical aberration and chromatic aberration that occur during focusing are corrected by moving the focus group, which is composed of a cemented lens element consisting of a positive lens and a negative lens. Japanese Patent Application Laid-Open No. 2006-129999 discloses a zoom lens that employs a so-called floating focus system in which two focus groups are moved during focusing. In this zoom lens, the weight of each focus group is reduced by locating the two focus groups closer to the image side than the aperture stop.

[0004] Patent Document 1: WO-A1-2019 / 131993 Patent Document 2: JP 2018-92185 A

[0005] However, in the zoom lens disclosed in Patent Document 1, the focus group is located within the first lens group, which has a relatively large beam diameter, and therefore the focus group has a large diameter, making it difficult to perform quiet, high-speed focusing. Furthermore, the optical performance changes significantly due to fluctuations in axial chromatic aberration and other aberrations during focusing, making it difficult to achieve high optical performance at all object distances. Similarly, in the zoom lens disclosed in Patent Document 2, the optical performance changes significantly due to fluctuations in field curvature aberration, lateral chromatic aberration, and other aberrations during focusing, making it difficult to achieve high optical performance at all object distances.

[0006] The present invention provides a zoom lens that can achieve high optical performance over the entire zoom range and at all object distances while reducing the weight of the focus group, and an imaging apparatus equipped with the same.

[0007] A zoom lens according to one aspect of the present invention has, arranged in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, and multiple subsequent lens groups, and the spacing between adjacent lens groups changes during zooming. The first lens group does not move during zooming, and the second lens group moves during zooming. The multiple subsequent lens groups include a first focus group that moves during zooming and focusing, and a second focus group located closer to the image than the first focus group. When the focal length of the first focus group is ff1, the focal length of the second focus group is ff2, the distance on the optical axis from the object-side surface of the first lens closest to the object in the zoom lens when focused on an object at infinity at the wide-angle end to the image plane is TTL, and the distance on the optical axis from the image-side surface of the lens closest to the image in the first focus group when focused on an object at infinity at the wide-angle end to the image plane is Lff1w, the following conditions are satisfied: 0<|ff2 / ff1|≦0.95 0.45≦Lff1w / TTL≦0.80

[0008] Another aspect of the present invention provides a zoom lens having, arranged in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, and multiple subsequent lens groups, wherein the spacing between adjacent lens groups changes during zooming. The first lens group does not move during zooming, the second lens group moves during zooming, and the multiple subsequent lens groups include a first focus group and a second focus group located closer to the image than the first focus group, which move during zooming and focusing, respectively. The zoom lens satisfies the following condition: 0.80≦|Mfc2 / Mfc1|≦8.00, where Mfc1 is the amount of movement of the first focus group during focusing from infinity to the closest distance at the telephoto end, and Mfc2 is the amount of movement of the second focus group during focusing from infinity to the closest distance at the telephoto end. An imaging device equipped with the zoom lens also constitutes another aspect of the present invention.

[0009] According to the present invention, it is possible to provide a zoom lens that can achieve high optical performance over the entire zoom range and at all object distances while reducing the weight of the focus group.

[0010] 1A and 1B are cross-sectional views of the zoom lens of Example 1 at (A) the wide-angle end and (B) the telephoto end in a state where the lens is focused at infinity. 2A and 2B are longitudinal aberration diagrams of the zoom lens of Example 1 at (A) the wide-angle end and (B) the telephoto end in a state where the lens is focused at infinity. 3A and 3B are longitudinal aberration diagrams of the zoom lens of Example 1 at (A) the wide-angle end and (B) the telephoto end in a state where the lens is focused at the closest point. 4A and 4B are cross-sectional views of the zoom lens of Example 2 at (A) the wide-angle end and (B) the telephoto end in a state where the lens is focused at infinity. 5A and 5B are longitudinal aberration diagrams of the zoom lens of Example 2 at (A) the wide-angle end and (B) the telephoto end in a state where the lens is focused at infinity. 6A and 6B are longitudinal aberration diagrams of the zoom lens of Example 3 at (A) the wide-angle end and (B) the telephoto end in a state where the lens is focused at infinity. 10A and 10B are longitudinal aberration diagrams of the zoom lens of Example 3 at (A) the wide-angle end and (B) the telephoto end in a state focused at infinity. 10B are longitudinal aberration diagrams of the zoom lens of Example 3 at (A) the wide-angle end and (B) the telephoto end in a state focused at the closest point. 10C are cross-sectional views of the zoom lens of Example 4 at (A) the wide-angle end and (B) the telephoto end in a state focused at infinity. 10C are longitudinal aberration diagrams of the zoom lens of Example 4 at (A) the wide-angle end and (B) the telephoto end in a state focused at infinity. 10C are cross-sectional views of the zoom lens of Example 5 at (A) the wide-angle end and (B) the telephoto end in a state focused at infinity. 10C are longitudinal aberration diagrams of the zoom lens of Example 5 at (A) the wide-angle end and (B) the telephoto end in a state focused at infinity. 10A and 10B are longitudinal aberration diagrams at (A) the wide-angle end and (B) the telephoto end in a closest focus state of the zoom lens of Example 5. FIG. 10B are cross-sectional views of the zoom lens of Example 6 at (A) the wide-angle end and (B) the telephoto end in a closest focus state of the zoom lens of Example 6. FIG. 10C are longitudinal aberration diagrams of the zoom lens of Example 6 at (A) the wide-angle end and (B) the telephoto end in a closest focus state of the zoom lens of Example 6. FIG. 10C are longitudinal aberration diagrams of the zoom lens of Example 6 at (A) the wide-angle end and (B) the telephoto end in a closest focus state of the zoom lens of Examples 1 to 6.

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, prior to the specific description of embodiments 1 to 6, matters common to all embodiments will be described.

[0012] 1, 4, 7, 10, 13, and 16 show cross sections of the zoom lens L0 of Examples 1 to 6 at (A) the wide-angle end and (B) the telephoto end when the lens is focused on an object at infinity (hereinafter referred to as the infinity focused state), respectively. In each figure, the left side is the object side (front side), and the right side is the image side (rear side).

[0013] In a zoom lens, a lens group is a group of one or more lenses that may or may not move as a unit during zooming (variable magnification) between the wide-angle end and the telephoto end. That is, the spacing between adjacent lens groups changes during zooming. The lens group may include an aperture stop. The wide-angle end and the telephoto end respectively indicate the zoom states with the maximum angle of view (shortest focal length) and the minimum angle of view (maximum focal length) when the lens group that moves during zooming is located at the ends of its mechanically or controllably movable range on the optical axis.

[0014] In each figure, Li (i = 1 to 8) indicates the i-th lens group in the zoom lens L0, counting from the object side. SP indicates the aperture stop, and IP indicates the image plane. The image plane IP is where the imaging surface (light-receiving surface) of an imaging element such as a CCD sensor or CMOS sensor, or the film surface (photosensitive surface) of a silver halide film, is located.

[0015] The zoom lens L0 in each embodiment has, arranged in order from the object side to the image side, a first lens unit L1 with positive refractive power, a second lens unit L2 with negative refractive power, and multiple subsequent lens units (L3 onward). The first lens unit L1 does not move during zooming, while the second lens unit L2 moves during zooming. The multiple subsequent lens units include a first focus unit Lfc1 and a second focus unit Lfc2 located closer to the image than the first focus unit Lfc1, which move during zooming and focusing, respectively. In each figure, the arrow "focus" indicates the direction of movement of each focus unit during focusing from infinity to the closest point.

[0016] The first lens unit L0, which is closest to the object, has positive refractive power, resulting in a telephoto power arrangement, and by converging light rays at the first lens unit L0, it is possible to prevent the lens diameters of the first focus unit Lfc1 and the second focus unit Lfc2, which are located closer to the image than the first lens unit L0, from increasing. Furthermore, because the first lens unit L0 does not move during zooming, fluctuations in various aberrations such as spherical aberration and curvature of field are suppressed at all object distances over the entire zoom range.

[0017] Furthermore, since the second lens unit L2 has negative refractive power, it is possible to easily correct various aberrations such as spherical aberration and curvature of field at all object distances over the entire zoom range. Furthermore, since the first focus unit Lfc1 and the second focus unit Lfc2 move during zooming and focusing, it is possible to easily correct various aberrations such as spherical aberration, axial chromatic aberration, and curvature of field that accompany zooming and focusing.

[0018] In the above configuration, the focal length of the first focus unit Lfc1 is defined as ff1, and the focal length of the second focus unit Lfc2 is defined as ff2. The distance on the optical axis (total lens length) from the object-side surface of the first lens closest to the object in the zoom lens L0 at the wide-angle end and in a state focused at infinity to the image plane IP is defined as TTL, and the distance on the optical axis from the image-side surface of the lens closest to the image in the first focus unit Lfc1 at the wide-angle end and in a state focused at infinity to the image plane IP is defined as Lff1w. In this case, the zoom lens L0 in each embodiment satisfies the conditions of the following expressions (1) and (2).

[0019] 0<|ff2 / ff1|≦0.95 (1) 0.45≦Lff1w / TTL≦0.80 (2) The condition in formula (1) indicates an appropriate relationship between the focal length ff1 of the first focus unit Lfc1 and the focal length ff2 of the second focus unit Lfc2. When |ff2 / ff1| reaches the lower limit of formula (1), 0, the second focus unit Lfc2 loses its refractive power, making it difficult to properly correct various aberrations such as spherical aberration, axial chromatic aberration, and curvature aberration at all object distances, which is undesirable. When |ff2 / ff1| exceeds the upper limit of formula (1), the refractive power of the first focus unit Lfc1 becomes too strong, making it difficult to properly correct various aberrations such as spherical aberration, axial chromatic aberration, and curvature of field at all object distances, which is undesirable.

[0020] The condition of formula (2) indicates the appropriate relationship between the total lens length TTL at the wide-angle end and in the infinity-focused state and the distance Lff1w from the image-side surface of the lens closest to the image in the first focus group Lfc1 to the image plane IP. If Lff1w / TTL falls below the lower limit of formula (2), the first focus group Lfc1 will be positioned closer to the image plane where the axial light beam diameter is smaller. As a result, the sensitivity of the first focus group Lfc1 to spherical aberration and axial chromatic aberration due to movement will be too low. This makes it difficult for the first focus group Lfc1 to adequately correct fluctuations in the aberrations that occur during focusing, which is undesirable. If Lff1w / TTL exceeds the upper limit value of equation (2), the first focus group Lfc1 will be positioned on the object side where the axial light beam diameter is large, which results in a larger lens diameter of the first focus group Lfc1 and makes it difficult to reduce the weight of the first focus group Lfc1, which is undesirable.

[0021] By satisfying the above configuration and conditions, it is possible to realize a zoom lens L0 that can achieve high optical performance over the entire zoom range and at all object distances while reducing the weight of each focus group.

[0022] It is more preferable that the numerical ranges of the formulas (1) and (2) are as follows:

[0023] 0.01≦|ff2 / ff1|≦0.75 (1a) 0.48≦Lff1w / TTL≦0.70 (2a) It is more preferable to set the numerical ranges of the formulas (1) and (2) as follows.

[0024] 0.03≦|ff2 / ff1|≦0.65 (1b) 0.50≦Lff1w / TTL≦0.65 (2b) Furthermore, it is preferable that the zoom lens L0 in each embodiment satisfy at least one of the conditions in the following expressions (3) to (13). Here, the focal length of the second lens unit L2 is f2, and the distance on the optical axis from the image-side surface of the lens closest to the image in the second focus unit Lfc1 at the wide-angle end and in a state focused at infinity to the image plane IP is Lff2w. The amount of movement of the first focus unit Lfc1 during focusing from infinity to the closest distance at the telephoto end is Mfc1, and the amount of movement of the first focus unit Lfc1 during zooming from the wide-angle end to the telephoto end when focused at infinity is Mzf1. The movement amount of the second focus group Lfc2 for focusing from infinity to the closest object at the telephoto end is Mfc2, and the movement amount of the second focus group Lfc2 during zooming from the wide-angle end to the telephoto end in the infinity-focused state is Mzf2. The movement amount of the lens group during focusing is the difference between the position of the lens group in the infinity-focused state and the position of the lens group in the state focused on the closest object (hereinafter referred to as the closest-focused state), and does not include the amount of reciprocating movement, and is considered positive when the lens group is located closer to the image in the closest-focused state than in the infinity-focused state. The movement amount of the lens group during zooming is the difference between the position of the lens group at the wide-angle end and the position of the lens group at the telephoto end, and does not include the amount of reciprocating movement, and is considered positive when the lens group is located closer to the image at the telephoto end than in the wide-angle end.

[0025] DLt is the distance (thickness) on the optical axis from the object-side surface of the lens closest to the object in the final lens unit Lst, which is closest to the image side among the multiple subsequent lens units, to the image-side surface of the lens closest to the image in the final lens unit Lst. BF is the air-equivalent distance (back focus) on the optical axis from the image-side surface of the lens closest to the image in the final lens unit Lst at the wide-angle end and in a state focused at infinity to the image plane IP. ft is the focal length of the entire zoom lens L0 at the telephoto end and in a state focused at infinity, f1 is the focal length of the first lens unit L1, and fLt is the focal length of the final lens unit Lst. Dsp is the distance on the optical axis from the aperture stop SP to the image plane IP at the wide-angle end and in a state focused at infinity.

[0026] 0<|f2 / ff1|≦2.00 (3) 0.20≦Lff2w / TTL≦0.45 (4) 0.50≦|f2 / ff2|≦3.50 (5) 0.25≦|Мfc1 / Мzf1|≦1.50 (6) 0.80≦|Мfc2 / Мfc2|≦3.00 (7) 0.80≦|Мfc2 / Мfc1|≦8.00 (8) 0.80≦DLt / BF≦2.50 (9) 0.30≦TTL / ft≦1.10 (10) 0<|f1 / ff1|≦1.50 (11) 0<|ff2 / fLt|≦1.20 (12) 0.35≦|Dsp / TTL|≦0.70 (13) The condition in equation (3) indicates an appropriate relationship between the focal length f2 of the second lens unit L2 and the focal length ff1 of the first focus unit Lfc1. When |f2 / ff1| reaches 0, the lower limit of equation (3), the second lens unit L2 loses its refractive power, making zooming difficult, which is undesirable. Also, when |f2 / ff1| exceeds the upper limit of equation (3), the refractive power of the first focus unit Lfc1 becomes too strong, making it difficult to effectively correct various aberrations such as spherical aberration, axial chromatic aberration, and curvature of field at all object distances, which is undesirable.

[0027] The condition of formula (4) indicates the appropriate relationship between the distance Lff2w from the image-side surface of the lens closest to the image in the second focus group Lfc2 to the image plane IP when the lens is at the wide-angle end and focused at infinity, and the distance TTL from the object-side surface of the first lens to the image plane IP. If Lff2w / TTL falls below the lower limit of formula (4), the second focus group Lfc2 will be positioned on the image side, and the amount of field curvature and lateral chromatic aberration generated by the second focus group Lfc2 will be too large compared to the amount generated by the first focus group Lfc1, making it difficult to effectively correct them, which is undesirable. If Lff2w / TTL exceeds the upper limit of formula (4), the second focus group Lfc2 will be positioned on the object side, which is advantageous for correcting spherical aberration and axial chromatic aberration. However, the amount of field curvature generated by the second focus group Lfc2 will be too small. As a result, it becomes difficult to suppress fluctuations in the curvature of field of the zoom lens L0 that occur during focusing, which is undesirable.

[0028] The condition of formula (5) indicates an appropriate relationship between the focal length f2 of the second lens unit L2 and the focal length ff2 of the second focus unit Lfc2. If |f2 / ff2| falls below the lower limit of formula (5), the refractive power of the second focus unit Lfc2 becomes too weak, making it difficult to properly correct various aberrations such as spherical aberration, axial chromatic aberration, and curvature of field at all object distances, which is undesirable. If |f2 / ff2| exceeds the upper limit of formula (5), the refractive power of the second focus unit Lfc2 becomes too strong, increasing the amount of various aberrations such as spherical aberration, axial chromatic aberration, and curvature of field at the second focus unit Lfc2, which is undesirable, making it difficult to properly correct them at all object distances.

[0029] The condition of equation (6) indicates the appropriate relationship between the movement amount Mfc1 of the first focus group Lfc1 during focusing from infinity to the closest distance at the telephoto end and the movement amount Mzf1 of the first focus group Lfc1 during zooming from the wide-angle end to the telephoto end while focused at infinity. If |Mfc1 / Mzf1| falls below the lower limit of equation (6), the movement amount of the first focus group Lfc1 during focusing becomes too small, making it difficult to correct various aberrations such as spherical aberration and axial chromatic aberration, which is undesirable. If |Mfc1 / Mzf1| exceeds the upper limit of equation (6), the movement amount of the first focus group Lfc1 during focusing becomes too large, and increasing the lens group spacing to ensure this movement amount increases the overall length of the zoom lens L0. This is undesirable because it makes it difficult to reduce the size of the zoom lens L0.

[0030] The condition of equation (7) indicates the appropriate relationship between the amount of movement Mfc2 of the second focus group Lfc2 during focusing from infinity to the closest distance at the telephoto end and the amount of movement Mzf2 of the second focus group Lfc2 during zooming from the wide-angle end to the telephoto end while focused at infinity. If |Mfc2 / Mzf2| falls below the lower limit of equation (7), the amount of movement of the second focus group Lfc2 during focusing becomes too small, making it difficult to correct various aberrations such as spherical aberration, axial chromatic aberration, and field curvature aberration. This is undesirable. If |Mfc2 / Mzf2| exceeds the upper limit of equation (7), the amount of movement of the second focus group Lfc2 during zooming becomes too small, making it necessary to increase the refractive power of the second focus group Lfc2 to obtain a sufficient zoom ratio. As a result, it becomes difficult to properly correct various aberrations such as spherical aberration, axial chromatic aberration, and curvature of field during focusing, which is undesirable.

[0031] The condition of equation (8) indicates the appropriate relationship between the movement amount Mfc2 of the second focus unit Lfc2 and the movement amount Mfc1 of the first focus unit Lfc1 during focusing from infinity to the closest distance at the telephoto end. If |Mfc2 / Mfc1| falls below the lower limit of equation (8), the movement amount of the first focus unit Lfc1 becomes large, and the amount of spherical aberration and axial chromatic aberration generated during focusing becomes too large. This makes it difficult to correct spherical aberration and axial chromatic aberration with the second focus unit Lfc2, which is undesirable. If |Mfc2 / Mfc1| exceeds the upper limit of equation (8), the movement amount of the second focus unit Lfc2 becomes large, and the amount of spherical aberration, axial chromatic aberration, and curvature of field generated during focusing becomes too large. As a result, it becomes difficult to correct spherical aberration, axial chromatic aberration, and field curvature with the first focus unit Lfc1, which is not preferable.

[0032] The condition of formula (9) shows the appropriate relationship between the thickness DLt of the final lens unit Lst and the back focal length BF at the wide-angle end and infinity focus state. If DLt / BF is below the lower limit of formula (9), the thickness of the final lens unit Lst becomes too small, making it difficult to secure space for inserting an optical unit such as a built-in converter into the final lens unit Lst, which is undesirable. If DLt / BF is above the upper limit of formula (9), the back focal length becomes too short, making it difficult to use an optical unit such as a rear converter, which is undesirable.

[0033] The condition of formula (10) shows the appropriate relationship between the total lens length TTL at the wide-angle end when focused at infinity and the focal length ft of the entire zoom lens L0 system when focused at the telephoto end and at infinity. If TTL / ft is below the lower limit of formula (10), the refractive power of each lens group becomes too strong, making it difficult to obtain good optical performance, which is undesirable. If TTL / ft is above the upper limit of formula (10), the refractive power of each lens group becomes too weak, increasing the total lens length and making it difficult to reduce the size of the zoom lens L0, which is undesirable.

[0034] The condition of equation (11) indicates an appropriate relationship between the focal length f1 of the first lens unit L1 and the focal length ff1 of the first focus unit Lfc1. When |f1 / ff1| reaches the lower limit of equation (11), 0, the converging action of the first lens unit Lfc1 is lost, and the lens diameters of the first focus unit Lfc1 and the second focus unit Lfc2, which are arranged closer to the image than the first lens unit L1, become larger. As a result, it becomes difficult to reduce the size of each focus unit, which is undesirable. When |f1 / ff1| exceeds the upper limit of equation (11), the refractive power of the first focus unit Lfc1 becomes too strong, which makes it difficult to correct various aberrations such as spherical aberration and axial chromatic aberration, which is also undesirable.

[0035] The condition of equation (12) indicates an appropriate relationship between the focal length ff2 of the second focus unit Lfc2 and the focal length fLt of the final lens unit Lst. When |ff2 / fLt| reaches the lower limit of equation (12), 0, the second focus unit Lfc2 loses its refractive power, making it difficult to properly correct various aberrations, such as spherical aberration, axial chromatic aberration, and curvature of field, during focusing, which is undesirable. When |ff2 / fLt| exceeds the upper limit of equation (12), the refractive power of the second focus unit Lfc2 becomes too weak, making it difficult to properly correct various aberrations, such as spherical aberration, axial chromatic aberration, and curvature of field, during focusing, which is undesirable.

[0036] The condition of equation (13) indicates the appropriate relationship between the distance Dsp from the aperture stop SP to the image plane IP and the total lens length TTL when the lens is at the wide-angle end and focused at infinity. If |Dsp / TTL| falls below the lower limit of equation (13), the aperture stop SP becomes too close to the imaging plane of the image sensor located at the image plane IP, increasing the angle of incidence of light rays incident on the imaging plane. This results in a decrease in the light-gathering efficiency of the image sensor, which is undesirable. Furthermore, the lens diameter of the first lens unit L1 becomes large, making it difficult to miniaturize the zoom lens L0, which is undesirable. If |Dsp / TTL| exceeds the upper limit of equation (13), the aperture stop SP becomes too close to the object side, increasing the aperture stop diameter, making it difficult to miniaturize the zoom lens L0, which is undesirable.

[0037] It is more preferable to set the numerical ranges of the formulas (3) to (13) as follows:

[0038] 0.01≦|f2 / ff1|≦1.80 (3a) 0.28≦Lff2w / TTL≦0.43 (4a) 0.70≦|f2 / ff2|≦3.10 (5a) 0.32≦|Мfc1 / Мfc1|≦1.20 (6a) 1.10≦|Мfc2 / Мzf2|≦2.50 (7a) 1.00≦|Мfc2 / Мfc1|≦7.40 (8a) 1.10≦DLt / BF≦2.10 (9a) 0.50≦TTL / ft≦0.95 (10a) 0.08≦|f1 / ff1|≦1.30 (11a) 0.05≦|ff2 / fLt|≦0.95 (12a) 0.43≦|Dsp / TTL|≦0.60 (13a) Furthermore, it is more preferable to set the numerical ranges of the formulas (3) to (13) as follows.

[0039] 0.03≦|f2 / ff1|≦1.75 (3b) 0.32≦Lff2w / TTL≦0.41 (4b) 0.80≦|f2 / ff2|≦3.00 (5b) 0.35≦|Мfc1 / Мfc1|≦1.10 (6b) 1.30≦|Мfc2 / Мzf2|≦2.30 (7b) 1.10≦|Мfc2 / Мfc1|≦7.10 (8b) 1.20≦DLt / BF≦1.90 (9b) 0.60≦TTL / ft≦0.90 (10b) 0.12≦|f1 / ff1|≦1.20 (11b) 0.08≦|ff2 / fLt|≦0.85 (12b) 0.45≦|Dsp / TTL|≦0.55 (13b) Furthermore, it is preferable that the zoom lens L0 of each embodiment has at least one of the following configurations.

[0040] It is preferable that the direction of movement of the first focus group Lfc1 during focusing from infinity to the closest distance in all zoom states from the wide-angle end to the telephoto end be different from the direction of movement of the first focus group Lfc1 during zooming from the wide-angle end to the telephoto end in the infinity-focused state. This makes it easy to ensure movement space for the first focus group Lfc1 during focusing in each zoom state, and enables aberration correction without making the refractive power of the first focus group Lfc too strong. As a result, it becomes easy to correct various aberrations such as spherical aberration and axial chromatic aberration, and to suppress aberration fluctuations during focusing.

[0041] Furthermore, it is preferable that the direction of movement of the second focus group Lfc2 during focusing from infinity to the closest distance in all zoom states is different from the direction of movement of the second focus group Lfc2 during zooming from the wide-angle end to the telephoto end in the infinity-focused state. This makes it easy to ensure a movement space for the second focus group Lfc2 during focusing in each zoom state, and enables focusing without making the refractive power of the second focus group Lfc2 too strong. As a result, it becomes easy to correct various aberrations such as spherical aberration and axial chromatic aberration, and to suppress aberration fluctuations during focusing.

[0042] It is also preferable that the first lens unit L1 be composed of three or fewer lenses, which makes it easier to reduce the weight of the zoom lens L0.

[0043] It is also preferable that the first focus group Lfc1 be configured with two or less lenses, which makes it easier to reduce the weight of the first focus group Lfc1 and perform quiet, high-speed focusing.

[0044] Similarly, it is preferable that the second focus group Lfc2 be composed of two or less lenses, which makes it easier to reduce the weight of the second focus group Lfc2 and perform quiet, high-speed focusing.

[0045] Furthermore, it is preferable that the final lens unit Lst does not move during zooming, which makes it possible to suppress fluctuations in various aberrations, such as field curvature, at the final lens unit Lst during zooming and also makes it easier to insert and remove optical units, such as a built-in converter.

[0046] In the zoom lens L0 of each embodiment, the entire lens group with negative refractive power located closer to the image side than the aperture stop SP, or a subgroup with negative refractive power, which is a part of the lens group, may be moved (shifted) relative to the optical axis to reduce image blur caused by vibrations such as camera shake.

[0047] The specific configuration of the zoom lens L0 of each embodiment will be described below.

[0048] The zoom lens L0 of Example 1 shown in FIG. 1 is composed of, arranged in order from the object side to the image side, a first lens unit L1 with positive refractive power, a second lens unit L2 with negative refractive power, a third lens unit L3 with positive refractive power, a fourth lens unit L4 with negative refractive power which is the first focus unit Lfc1, a fifth lens unit L5 with negative refractive power, a sixth lens unit L6 with positive refractive power which is the second focus unit Lfc2, and a seventh lens unit L7 with negative refractive power which is the final lens unit Lst.

[0049] During focusing from infinity to the closest distance in each zoom state, the first focus unit Lfc1 (fourth lens unit L4) and the second focus unit Lfc2 (sixth lens unit L6) each move toward the object side. During zooming from the wide-angle end to the telephoto end, the first lens unit L1, the third lens unit L3, the fifth lens unit L5, and the seventh lens unit L7 do not move, and the second lens unit L2, the fourth lens unit L4, and the sixth lens unit L6 each move toward the image side.

[0050] The zoom lens L0 of Example 2 shown in Figure 4 is composed of, arranged in order from the object side to the image side, a first lens unit L1 with positive refractive power, a second lens unit L2 with negative refractive power, a third lens unit L3 with positive refractive power, a fourth lens unit L4 with positive refractive power, a fifth lens unit L5 with negative refractive power which is the first focus unit Lfc1, a sixth lens unit L6 with positive refractive power, a seventh lens unit L7 with positive refractive power which is the second focus unit Lfc2, and an eighth lens unit L8 with negative refractive power which is the final lens unit Lst.

[0051] During focusing from infinity to the closest distance in each zoom state, the first focus unit Lfc1 (fifth lens unit L5) and the second focus unit Lfc2 (seventh lens unit L7) each move toward the object side. During zooming from the wide-angle end to the telephoto end, the first lens unit L1, the fourth lens unit L4, the sixth lens unit L6, and the eighth lens unit L8 do not move, and the second lens unit L2, the third lens unit L3, the fifth lens unit L5, and the seventh lens unit L7 each move toward the image side.

[0052] The zoom lens L0 of Example 3 shown in Figure 7 is composed of, arranged in order from the object side to the image side, a first lens unit L1 with positive refractive power, a second lens unit L2 with negative refractive power, a third lens unit L3 with negative refractive power, a fourth lens unit L4 with positive refractive power, a fifth lens unit L5 with negative refractive power which is the first focus unit Lfc1, a sixth lens unit L6 with positive refractive power, a seventh lens unit L7 with positive refractive power which is the second focus unit Lfc2, and an eighth lens unit L8 with negative refractive power which is the final lens unit Lst.

[0053] During focusing from infinity to the closest distance in each zoom state, the first focus unit Lfc1 (fifth lens unit L5) and the second focus unit Lfc2 (seventh lens unit L7) each move toward the object side. During zooming from the wide-angle end to the telephoto end, the first lens unit L1, the fourth lens unit L4, the sixth lens unit L6, and the eighth lens unit L8 do not move, and the second lens unit L2, the third lens unit L3, the fifth lens unit L5, and the seventh lens unit L7 each move toward the image side.

[0054] The zoom lens L0 of Example 4 shown in Figure 10 is composed of, arranged in order from the object side to the image side, a first lens unit L1 with positive refractive power, a second lens unit L2 with negative refractive power, a third lens unit L3 with positive refractive power, a fourth lens unit L4 with negative refractive power which is the first focus unit Lfc1, a fifth lens unit L5 with positive refractive power, a sixth lens unit L6 with negative refractive power which is the second focus unit Lfc2, and a seventh lens unit L7 with positive refractive power which is the final lens unit Lst.

[0055] During focusing from infinity to the closest distance in each zoom state, the first focus unit Lfc1 (fourth lens unit L4) moves toward the object side, and the second focus unit Lfc2 (sixth lens unit L6) moves toward the image side. During zooming from the wide-angle end to the telephoto end, the first lens unit L1, the third lens unit L3, the fifth lens unit L5, and the seventh lens unit L7 do not move, the second lens unit L2 and the fourth lens unit L4 move toward the image side, and the sixth lens unit L6 moves toward the object side.

[0056] The zoom lens L0 of Example 5 shown in Figure 13 is composed of, arranged in order from the object side to the image side, a first lens unit L1 with positive refractive power, a second lens unit L2 with negative refractive power, a third lens unit L3 with positive refractive power, a fourth lens unit L4 with positive refractive power which is the first focus unit Lfc1, a fifth lens unit L5 with negative refractive power, a sixth lens unit L6 with positive refractive power which is the second focus unit Lfc2, and a seventh lens unit L7 with positive refractive power which is the final lens unit Lst.

[0057] During focusing from infinity to the closest distance in each zoom state, the first focus unit Lfc1 (fourth lens unit L4) moves toward the image side, and the second focus unit Lfc2 (sixth lens unit L6) moves toward the object side. During zooming from the wide-angle end to the telephoto end, the first lens unit L1, the third lens unit L3, the fifth lens unit L5, and the seventh lens unit L7 do not move, the second lens unit L2 and the sixth lens unit L6 move toward the image side, and the fourth lens unit L4 moves toward the object side.

[0058] The zoom lens L0 of Example 6 shown in Figure 16 is composed of, arranged in order from the object side to the image side, a first lens unit L1 with positive refractive power, a second lens unit L2 with negative refractive power, a third lens unit L3 with positive refractive power, a fourth lens unit L4 with positive refractive power which is the first focus unit Lfc1, a fifth lens unit L5 with positive refractive power, a sixth lens unit L6 with negative refractive power which is the second focus unit Lfc2, and a seventh lens unit L7 with positive refractive power which is the final lens unit Lst.

[0059] During focusing from infinity to the closest distance in each zoom state, the first focus unit Lfc1 (fourth lens unit L4) and the second focus unit Lfc2 (sixth lens unit L6) each move toward the image side. During zooming from the wide-angle end to the telephoto end, the first lens unit L1, the third lens unit L3, the fifth lens unit L5, and the seventh lens unit L7 do not move, the second lens unit L2 moves toward the image side, and the fourth lens unit L4 and the sixth lens unit L6 each move toward the object side.

[0060] Numerical Examples 1 to 6 corresponding to Examples 1 to 6, respectively, are shown below. In each numerical example, surface number i indicates the order of the surface when counted from the object side. r is the radius of curvature (mm) of the ith surface from the object side, d is the lens thickness or air gap (mm) on the optical axis between the ith and (i+1)th surfaces, and nd is the refractive index at the d-line of the optical material between the ith and (i+1)th surfaces. νd is the Abbe number based on the d-line of the optical material between the ith and (i+1)th surfaces.

[0061] The Abbe number vd based on the d-line is expressed as vd=(Nd-1) / (NF-NC), where Nd, NF, and NC are the refractive indices at the d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) of the Fraunhofer lines.

[0062] In each numerical example, d, focal length (mm), F-number, and half angle of view (°) are all values ​​in the infinity-focused state. BF represents back focus (mm). Back focus is the distance on the optical axis from the lens surface (final surface) closest to the image of the zoom lens to the paraxial image plane, expressed as an air-equivalent length. The total lens length is the distance on the optical axis from the lens surface (foreground surface) closest to the object of the zoom lens to the final surface, plus the back focus. In each numerical example, the object distance in the closest focus state represents the distance on the optical axis from the image plane IP to the object.

[0063] The values ​​of the above-mentioned expressions (1) to (13) in Numerical Examples 1 to 6 are summarized in Tables 1 and 2. As shown in Table 2, the zoom lens L0 in each of the Numerical Examples satisfies all of the conditions of Expressions (1) to (13).

[0064] 2, 5, 8, 11, 14, and 17A each show longitudinal aberrations (spherical aberration, astigmatism, distortion, and chromatic aberration) of the zoom lens L0 of Numerical Examples 1 to 6 at the wide-angle end and in a state focused at infinity. Also, (B) in these figures shows longitudinal aberrations of the zoom lens L0 of Numerical Examples 1 to 6 at the telephoto end and in a state focused at infinity. 3, 6, 9, 12, 15, and 18A each show longitudinal aberrations of the zoom lens L0 of Numerical Examples 1 to 6 at the wide-angle end and in a state focused at infinity (object distance 1800 mm), and (B) shows longitudinal aberrations of the zoom lens L0 of Numerical Examples 1 to 6 at the telephoto end and in a state focused at infinity.

[0065] In the spherical aberration diagram, Fno indicates the F-number, the solid line indicates spherical aberration at the d-line (wavelength 587.6 nm), and the two-dot chain line indicates spherical aberration at the g-line (wavelength 435.8 nm). In the astigmatism diagram, the solid line S indicates astigmatism at the sagittal image plane, and the dashed line M indicates astigmatism at the meridional image plane. The distortion diagram shows distortion at the d-line. The chromatic aberration diagram shows chromatic aberration of magnification at the g-line. ω is the half angle of view (°). [Numerical example 1] Unit: mm Surface data Surface number rd nd νd 1 132.256 12.31 1.49700 81.5 2 -320.754 20.00 3 111.907 9.16 1.43387 95.1 4 -436.938 2.06 5 -246.616 2.00 1.65412 39.7 6 185.973 (Variable) 7 60.390 1.80 1.72342 38.0 8 39.294 6.85 9 -254.690 1.80 1.59282 68.6 10 111.022 0.15 11 59.077 3.37 2.00069 25.5 12 138.110 4.00 13 -105.274 1.80 1.61997 63.9 14 212.735 (Variable) 15 73.991 5.47 1.55032 75.5 16 -208.249 (Variable) 17 -69.741 1.90 1.49700 81.5 18 -101.181 (Variable) 19 (Aperture) ∞ 2.49 20 367.705 3.33 1.76385 48.5 21 -80.050 0.15 22 58.479 5.64 1.49700 81.5 23 -60.490 1.30 2.00069 25.5 24 83.258 2.86 25 226.768 3.61 1.96300 24.1 26 -50.977 1.20 1.91650 31.6 27 122.512 1.36 28 -259.399 1.20 1.90043 37.4 29 106.816 2.02 30 118.948 2.11 2.00069 25.5 31 -333.849 (variable) 32 63.185 2.82 1.65160 58.5 33 -320.575 (variable) 34 -293.675 1.15 1.49700 81.5 35 45.863 4.06 36 -78.000 1.20 1.49700 81.5 37 32.090 3.64 1.61340 44.3 38 342.490 49.91 39 70.763 8.41 1.51742 52.4 40 -49.234 1.50 1.77250 49.6 41 -394.894 44.92 Image plane ∞ Various data Zoom ratio 2.36 Wide angle Mid-range Telephoto Focal length 205.13 302.70 484.90 F-number 5.77 5.77 5.77 Half angle of view (°) 6.02 4.09 2.55 Image height 21.64 21.64 21.64 Total lens length 343.36 343.36 343.36 BF 44.92 44.92 44.92 Focused at infinity d 6 2.14 29.88 57.61 d14 56.72 28.98 1.25 d16 6.72 12.67 30.40 d18 31.63 25.67 7.95 d31 9.51 11.66 27.16 d33 19.11 16.96 1.46 Closest Focusing Object Distance -1800 -1800 -1800 d 6 2.14 29.88 57.61 d14 56.72 28.98 1.25 d16 3.58 7.06 16.95 d18 34.77 31.28 21.39 d31 4.43 1.22 1.49 d33 24.19 27.4 27.13 Lens Group Data Group Initial Surface Focal Length 1 1 218.72 2 7 -75.17 3 15 99.89 4 17 -460.85 5 19 -1348.50 6 32 81.24 7 34 -107.12 [Numerical example 2] Unit: mm Surface data Surface number rd nd νd 1 129.227 12.04 1.49700 81.5 2 -379.850 20.00 3 110.198 10.06 1.43387 95.1 4 -646.974 6.53 5 -239.475 2.00 1.65412 39.7 6 168.526 (Variable) 7 100.437 1.80 1.60300 65.4 8 47.393 5.46 9 -171.772 1.80 1.52841 76.5 10 159.742 (Variable) 11 65.211 4.42 1.76182 26.5 12 -1695.538 3.81 13 -138.990 1.80 1.90043 37.4 14 190.529 (Variable) 15 110.306 5.00 1.55032 75.5 16 -103.943 (Variable) 17 -56.541 1.90 1.49700 81.5 18 -95.440 (Variable) 19(Aperture) ∞ 2.00 20 597.982 3.59 1.76385 48.5 21 -69.229 0.15 22 73.950 5.48 1.49700 81.5 23 -56.101 1.30 2.00069 25.5 24 115.683 3.00 25 -555.203 3.60 1.96300 24.1 26 -42.652 1.20 1.91650 31.6 27 185.184 0.98 28 -422.715 1.20 1.90043 37.4 29 169.441 1.90 30 163.131 2.16 2.00069 25.5 31 -223.450 (Variable) 32 69.202 2.86 1.65160 58.5 33 -339.648 (Variable) 34 131.945 1.15 1.49700 81.5 35 33.915 6.45 36 -92.960 1.20 1.49700 81.5 37 35.406 3.17 1.61340 44.3 38 185.171 56.93 39 70.750 6.48 1.53172 48.8 40 -114.001 1.50 1.69680 55.5 41 302.730 42.60 Image plane ∞ Various data Zoom ratio 2.35 Wide-angle Mid-range Telephoto Focal length 206.00 305.65 484.90 F-number 5.77 5.77 5.77 Half angle of view (°) 6.00 4.05 2.55 Image height 21.64 21.64 21.64 Lens length 343.36 343.36 343.36 BF 42.60 42.60 42.60 Focused at infinity d 6 2.00 32.01 62.02 d10 9.15 3.99 1.00 d14 53.12 28.27 1.25 d16 4.53 9.29 23.40 d18 20.37 15.61 1.50 d31 9.24 11.68 27.23 d33 19.43 16.98 1.43 Closest focus state Object distance -1800 -1800 -1800 d 6 2.00 32.01 62.02 d10 9.15 3.99 1.00 d14 53.12 28.27 1.25 d16 3.08 6.25 15.73 d18 21.83 18.65 9.17 d31 4.31 1.32 1.50 d33 24.35 27.35 27.17 Lens Group Data Group Initial Surface Focal Length 1 1 240.64 2 7 -75.50 3 11 559.42 4 15 98.06 5 17 -283.73 6 19 1379.19 7 32 88.47 8 34 -111.69 [Numerical Example 3] Unit: mm Surface Data Surface Number rd nd νd 1 120.167 14.77 1.48749 70.2 2 -447.658 20.00 3 100.603 11.74 1.43387 95.1 4 -439.581 1.76 5 -301.399 2.00 1.77047 29.7 6 243.489 (variable) 7 113.638 1.80 1.85150 40.8 8 46.463 8.04 9 -89.097 1.80 1.69680 55.5 10 179.633 0.15 11 92.468 6.13 1.92286 20.9 12 -119.436 (variable) 13 -71.723 1.80 1.85478 24.8 14 -630.274 (Variable) 15 142.944 5.46 1.69680 55.5 16 -100.152 (Variable) 17 -59.220 1.90 1.49700 81.5 18 -214.530 (Variable) 19 (Aperture) ∞ 2.40 20 -563.303 4.03 1.76385 48.5 21 -69.411 0.15 22 89.891 6.71 1.49700 81.5 23 -62.789 1.30 1.92286 20.9 24 215.758 1.90 25 94.056 6.06 1.96300 24.1 26 -54.205 1.20 1.91650 31.6 27 64.342 3.27 28 -159.413 1.20 2.00100 29.1 29 267.902 2.21 30 645.344 2.57 2.00069 25.5 31 -112.717 (Variable) 32 61.577 3.32 1.61800 63.4 33 -10826.171 (Variable) 34 -10766.126 3.00 1.61340 44.3 35 -88.017 1.20 1.49700 81.5 36 62.298 1.75 37 -536.388 1.15 1.49700 81.5 38 62.472 49.88 39 69.614 4.85 1.54814 45.8 40 449.113 44.88 Image plane ∞ Various data Zoom ratio 1.88 Wide angle Mid-range Telephoto Focal length 206.00 276.67 388.00 F-number 4.12 4.12 4.12 Half angle of view (°) 6.00 4.47 3.19 Image height 21.64 21.64 21.64 Total lens length 335.00 335.00 335.00 BF 44.88 44.88 44.88 Focused at infinity d 6 22.68 38.33 53.98 d12 6.36 7.70 10.51 d14 36.71 19.72 1.25 d16 4.50 7.19 9.33 d18 15.73 13.05 10.91 d31 9.51 14.02 27.21 d33 19.14 14.62 1.43 Closest focus state Object distance -1800 -1800 -1800 d 6 22.68 38.33 53.98 d12 6.36 7.70 10.51 d14 36.71 19.72 1.25 d16 3.20 4.82 5.58 d18 17.04 15.42 14.66 d31 2.04 0.78 1.50 d33 26.60 27.86 27.14 Lens group data Group Initial surface Focal length 1 1 192.10 2 7 -280.00 3 13 -94.82 4 15 85.30 5 17 -165.26 6 19 302.35 7 32 99.09 8 34 -266.60 [Numerical example 4] Unit: mm Surface data Surface number rd nd νd 1 122.688 12.98 1.49700 81.5 2 -308.770 20.00 3 102.661 8.93 1.43387 95.1 4 -678.666 1.57 5 -259.032 2.00 1.65412 39.7 6 163.689 (variable) 7 66.052 1.80 1.72342 38.0 8 37.129 6.28 9 -336.370 1.80 1.59282 68.6 10 101.497 0.15 11 55.235 3.47 2.00069 25.5 12 136.328 3.71 13 -93.877 1.80 1.61997 63.9 14 303.463 (variable) 15 59.595 5.40 1.55032 75.5 16 -502.704 (variable) 17 -58.403 1.90 1.61340 44.3 18 -87.061 (variable) 19(Aperture) ∞ 2.00 20 339.896 3.68 1.76385 48.5 21 -67.597 0.15 22 51.454 6.11 1.49700 81.5 23 -49.078 1.30 2.00069 25.5 24 108.444 2.53 25 408.521 3.13 1.76182 26.5 26 -56.156 1.20 1.74320 49.3 27 102.084 1.03 28 -7111.940 1.20 1.85478 24.8 29 88.039 1.89 30 62.498 2.75 2.00069 25.5 31 -271.212 (Variable) 32 -338.817 1.07 1.76385 48.5 33 28.954 2.13 1.65412 39.7 34 72.252 (Variable) 35 52.811 3.17 1.61340 44.3 36 168.645 1.40 1.49700 81.5 37 43.029 49.66 38 -93.971 1.20 1.49700 81.5 39 -258.161 0.20 40 2273.471 4.79 1.61340 44.3 41 -68.783 44.77 Image plane ∞ Various data Zoom ratio 2.37 Wide angle Mid-range Telephoto Focal length 204.24 309.00 484.90 F-number 5.77 5.77 5.77 Half angle of view (°) 6.05 4.01 2.55 Image height 21.64 21.64 21.64 Lens length 343.36 343.36 343.36 BF 44.77 44.77 44.77 Focused at infinity d 6 2.00 30.30 58.61 d14 57.86 29.55 1.25 d16 22.16 26.65 41.31 d18 20.65 16.16 1.50 d31 19.36 17.72 1.44 d34 14.21 15.85 32.13 Closest focus Object distance -1800 -1800 -1800 d 6 2.00 30.30 58.61 d14 57.86 29.55 1.25 d16 20.90 23.88 32.44 d18 21.91 18.93 10.37 d31 25.48 31.35 32.14 d34 8.09 2.22 1.43 Lens group data Group Initial surface Focal length 1 1 214.32 2 7 -70.68 3 15 97.15 4 17 -296.73 5 19 100.02 6 32 -65.85 7 35 178.26 [Numerical example 5] Unit: mm Surface data Surface number rd nd νd 1 104.138 13.59 1.49700 81.5 2 -433.415 20.00 3 111.297 7.20 1.43387 95.1 4 2575.811 5.41 5 -257.910 2.00 1.65412 39.7 6 166.491 (variable) 7 58.103 1.80 1.72342 38.0 8 34.829 5.13 9 379.623 1.80 1.59282 68.6 10 72.751 0.55 11 44.940 3.65 2.00069 25.5 12 78.743 4.36 13 -89.443 1.80 1.61997 63.9 14 2706.702 (Variable) 15 59.132 4.60 1.55032 75.5 16 -7262.003 (Variable) 17 -9923.682 1.00 1.83481 42.7 18 83.013 4.88 1.51742 52.4 19 -115.886 (Variable) 20 (Aperture) ∞ 2.00 21 79.113 2.43 1.76385 48.5 22 689.082 0.15 23 69.549 4.70 1.49700 81.5 24 -56.656 1.30 2.00069 25.5 25 115.181 1.90 26 92.948 3.51 1.96300 24.1 27 -53.632 1.20 1.91650 31.6 28 51.869 2.33 29 -82.620 1.20 1.90043 37.4 30 -981.056 1.90 31 309.459 1.98 2.00069 25.5 32 -105.970 (Variable) 33 49.948 3.53 1.49700 81.5 34 -157.959 (Variable) 35 877.760 1.15 1.49700 81.5 36 27.140 3.36 37 -77.809 1.20 1.49700 81.5 38 25.746 3.90 1.61340 44.3 39 140.622 49.88 40 99.320 9.49 1.65412 39.7 41 -62.320 1.50 1.92286 20.9 42 -107.225 42.99 Image plane ∞ Various data Zoom ratio 2.35 Wide angle Mid-range Telephoto Focal length 206.00 305.53 485.00 F-number 5.77 5.77 5.77 Half angle of view (°) 6.00 4.05 2.55 Image height 21.64 21.64 21.64 Lens length 343.36 343.36 343.36 BF 42.99 42.99 42.99 Focused at infinity d 6 2.00 32.11 62.21 d14 61.46 31.36 1.25 d16 22.94 9.37 1.50 d19 8.90 22.48 30.34 d32 9.18 12.34 27.28 d34 19.53 16.37 1.43 Closest focus state Object distance -1800 -1800 -1800 d 6 2.00 32.11 62.21 d14 61.46 31.36 1.25 d16 30.34 23.48 23.19 d19 1.50 8.36 8.65 d32 3.96 1.40 1.50 d34 24.75 27.31 27.21 Lens group data Group Initial surface Focal length 1 1 236.55 2 7 -81.79 3 15 106.61 4 17 1629.87 5 20 -300.94 6 33 76.79 7 35 721.93 [Numerical example 6] Unit: mm Surface data Surface number rd nd νd 1 132.062 12.16 1.49700 81.5 2 -339.513 20.00 3 133.207 8.00 1.43387 95.1 4 -542.488 3.05 5 -249.538 2.00 1.65412 39.7 6 225.088 (variable) 7 57.924 1.80 1.72342 38.0 8 37.907 6.08 9 -638.080 1.80 1.59282 68.6 10 116.398 0.15 11 51.881 3.21 2.00069 25.5 12 99.313 3.56 13 -142.679 1.80 1.61997 63.9 14 106.549 (Variable) 15 48.949 4.84 1.49700 81.5 16 214.820 (Variable) 17 107.070 1.00 1.75500 52.3 18 53.642 5.30 1.49700 81.5 19 -772.703 (Variable) 20(Aperture) ∞ 2.00 21 93.858 3.18 1.76385 48.5 22 -407.058 0.15 23 51.941 6.39 1.49700 81.5 24 -52.265 1.30 2.00069 25.5 25 77.241 2.25 26 105.216 4.72 1.78880 28.4 27 -40.959 1.20 1.67790 55.4 28 73.093 2.42 29 -85.651 1.20 1.85478 24.8 30 145.761 1.90 31 112.110 2.97 2.00069 25.5 32 -81.995 (Variable) 33 -364.084 1.07 1.72916 54.7 34 27.636 2.31 1.72047 34.7 35 65.695 (Variable) 36 97.222 3.17 1.65412 39.7 37 -249.221 1.40 1.49700 81.5 38 61.415 49.84 39 63.130 1.20 1.92286 20.9 40 49.903 4.75 1.51823 58.9 41 245.251 44.84 Image plane ∞ Various data Zoom ratio 2.42 Wide angle Mid-range Telephoto Focal length 200.65 309.00 485.00 F-number 5.77 5.77 5.77 Half angle of view (°) 6.15 4.01 2.55 Image height 21.64 21.64 21.64 Lens length 343.36 343.36 343.36 BF 44.84 44.84 44.84 Focused at infinity d 6 2.00 33.75 65.50 d14 64.75 33.00 1.25 d16 23.13 17.05 1.50 d19 2.90 8.98 24.53 d32 17.22 16.64 1.00 d35 20.36 20.93 36.57 Closest focus state Object distance -1800 -1800 -1800 d 6 2.00 33.75 65.50 d14 64.75 33.00 1.25 d16 24.53 20.04 9.54 d19 1.50 5.99 16.49 d32 23.48 31.46 35.73 d35 14.09 6.11 1.84 Lens group data Group Initial surface Focal length 1 1 233.13 2 7 -74.28 3 15 126.33 4 17 345.24 5 20 182.31 6 33 -75.01 7 36 250.89 .

[0066]

[0067]

[0068] [Imaging Device] FIG. 19 shows a digital camera as an imaging device equipped with the zoom lens L0 of Examples 1 to 6. Reference numeral 13 denotes a camera body, and reference numeral 11 denotes an imaging optical system constituted by the zoom lens L0 of Examples 1 to 6. Reference numeral 12 denotes an imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor that is built into the camera body 13 and photoelectrically converts the optical image formed by the imaging optical system 11 (i.e., captures an image of a subject through the zoom lens). The camera body 13 may be a single-lens reflex camera with a quick-turn mirror, or a mirrorless camera without a quick-turn mirror. The imaging optical system 11 may be detachable (replaceable) from the camera body 13, or may be integrally provided in the camera body.

[0069] In this way, by using the zoom lens L0 in each embodiment, it is possible to obtain an imaging device that is lightweight and capable of acquiring high-quality images over the entire zoom range and at all object distances.

[0070] The embodiments described above are merely representative examples, and various modifications and changes can be made to each embodiment when implementing the present invention.

Claims

1. A zoom lens having, arranged in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, and multiple subsequent lens groups, wherein the spacing between adjacent lens groups changes during zooming, wherein the first lens group does not move during zooming, and the second lens group moves during zooming, and the multiple subsequent lens groups include a first focus group and a second focus group located closer to the image than the first focus group, which move during zooming and focusing, respectively, and wherein the focal length of the first focus group is ff1, the focal length of the second focus group is ff2, the distance on the optical axis from the object-side surface of the first lens closest to the object in the zoom lens to the image plane when focused on an object at infinity at the wide-angle end is TTL, and the distance on the optical axis from the image-side surface of the lens closest to the image in the first focus group to the image plane when focused on an object at infinity at the wide-angle end is Lff1w, A zoom lens characterized by satisfying the following conditions: 0<|ff2 / ff1|≦0.95 0.45≦Lff1w / TTL≦0.

80.

2. The zoom lens according to claim 1, wherein the following condition is satisfied: 0<|f2 / ff1|≦2.00, where f2 is the focal length of the second lens group.

3. A zoom lens according to claim 1 or 2, characterized in that, when the wide-angle end is in focus on an object at infinity and the distance on the optical axis from the image-side surface of the lens closest to the image side in the second focus group to the image plane is Lff2w, the following condition is satisfied: 0.20≦Lff2w / TTL≦0.

45.

4. A zoom lens according to any one of claims 1 to 3, characterized in that the following condition is satisfied: 0.50≦|f2 / ff2|≦3.50, where f2 is the focal length of the second lens group.

5. A zoom lens according to any one of claims 1 to 4, characterized in that the following condition is satisfied: 0.25≦|Mfc1 / Mzf1|≦1.50, where Mfc1 is the amount of movement of the first focus group when focusing from infinity to the closest point at the telephoto end, and Mzf1 is the amount of movement of the first focus group when zooming from the wide-angle end to the telephoto end while focused on an object at infinity.

6. A zoom lens according to any one of claims 1 to 5, characterized in that the following condition is satisfied: 0.80≦|Mfc2 / Mzf2|≦3.00, where Mfc2 is the amount of movement of the second focus group when focusing from infinity to the closest point at the telephoto end, and Mzf2 is the amount of movement of the second focus group when zooming from the wide-angle end to the telephoto end while focused on an object at infinity.

7. A zoom lens according to any one of claims 1 to 6, characterized in that it satisfies the condition 0.80≦|Mfc2 / Mfc1|≦8.00, where Mfc1 is the amount of movement of the first focus group when focusing from infinity to the closest point at the telephoto end, and Mfc2 is the amount of movement of the second focus group when focusing from infinity to the closest point at the telephoto end.

8. A zoom lens according to any one of claims 1 to 7, characterized in that it satisfies the condition 0.80≦DLt / BF≦2.50, where DLt is the distance on the optical axis from the object-side surface of the lens closest to the object in the final lens group that is closest to the image among the plurality of subsequent lens groups to the image-side surface of the lens closest to the image in the final lens group, and BF is the air-equivalent distance on the optical axis from the image-side surface of the lens closest to the image in the final lens group at the wide-angle end and in a state focused on an object at infinity.

9. A zoom lens according to any one of claims 1 to 8, characterized in that it satisfies the condition 0.30≦TTL / ft≦1.10, where ft is the focal length of the zoom lens at the telephoto end and when focused on an object at infinity.

10. A zoom lens according to any one of claims 1 to 9, characterized in that the following condition is satisfied: 0<|f1 / ff1|≦1.50, where f1 is the focal length of the first lens group.

11. A zoom lens according to any one of claims 1 to 10, characterized in that the following condition is satisfied: 0<|ff2 / fLt|≦1.20, where fLt is the focal length of the final lens group closest to the image among the plurality of subsequent lens groups.

12. A zoom lens according to any one of claims 1 to 11, characterized in that it has an aperture stop, and satisfies the condition 0.35≦|Dsp / TTL|≦0.70, where Dsp is the distance on the optical axis from the aperture stop to the image plane when at the wide-angle end and focused on an object at infinity.

13. A zoom lens according to any one of claims 1 to 12, characterized in that the direction of movement of the first focus group when focusing from infinity to the closest point in all zoom states from the wide-angle end to the telephoto end is different from the direction of movement of the first focus group when zooming from the wide-angle end to the telephoto end while focused on an object at infinity.

14. A zoom lens according to any one of claims 1 to 13, characterized in that the direction of movement of the second focus group when focusing from infinity to the closest point in all zoom states from the wide-angle end to the telephoto end is different from the direction of movement of the second focus group when zooming from the wide-angle end to the telephoto end while focused on an object at infinity.

15. A zoom lens according to any one of claims 1 to 14, wherein the first lens group is composed of three or less lenses.

16. A zoom lens according to any one of claims 1 to 15, wherein the first focus group is composed of two or less lenses.

17. A zoom lens according to any one of claims 1 to 16, characterized in that the second focus group is composed of two or less lenses.

18. A zoom lens according to any one of claims 1 to 17, characterized in that the final lens group closest to the image among the plurality of subsequent lens groups does not move during zooming.

19. A zoom lens according to any one of claims 1 to 18, characterized in that it comprises, arranged in order from the object side to the image side, the first lens group, the second lens group, a third lens group with positive refractive power, a fourth lens group with negative refractive power, a fifth lens group with negative refractive power, a sixth lens group with positive refractive power, and a seventh lens group with negative refractive power, wherein the fourth lens group is the first focus group and the sixth lens group is the second focus group.

20. A zoom lens according to any one of claims 1 to 18, characterized in that it comprises, arranged in order from the object side to the image side, the first lens group, the second lens group, a third lens group with positive refractive power, a fourth lens group with positive refractive power, a fifth lens group with negative refractive power, a sixth lens group with positive refractive power, a seventh lens group with positive refractive power, and an eighth lens group with negative refractive power, wherein the fifth lens group is the first focus group and the seventh lens group is the second focus group.

21. A zoom lens according to any one of claims 1 to 18, characterized in that it comprises, arranged in order from the object side to the image side, the first lens group, the second lens group, a third lens group with negative refractive power, a fourth lens group with positive refractive power, a fifth lens group with negative refractive power, a sixth lens group with positive refractive power, a seventh lens group with positive refractive power, and an eighth lens group with negative refractive power, wherein the fifth lens group is the first focus group and the seventh lens group is the second focus group.

22. A zoom lens according to any one of claims 1 to 18, characterized in that it comprises, arranged in order from the object side to the image side, the first lens group, the second lens group, a third lens group with positive refractive power, a fourth lens group with negative refractive power, a fifth lens group with positive refractive power, a sixth lens group with negative refractive power, and a seventh lens group with positive refractive power, wherein the fourth lens group is the first focus group and the sixth lens group is the second focus group.

23. A zoom lens according to any one of claims 1 to 18, characterized in that it comprises, arranged in order from the object side to the image side, the first lens group, the second lens group, a third lens group with positive refractive power, a fourth lens group with positive refractive power, a fifth lens group with negative refractive power, a sixth lens group with positive refractive power, and a seventh lens group with positive refractive power, wherein the fourth lens group is the first focus group and the sixth lens group is the second focus group.

24. A zoom lens according to any one of claims 1 to 18, characterized in that it is composed of, arranged in order from the object side to the image side, the first lens group, the second lens group, a third lens group with positive refractive power, a fourth lens group with positive refractive power, a fifth lens group with positive refractive power, a sixth lens group with negative refractive power, and a seventh lens group with positive refractive power, wherein the fourth lens group is the first focus group and the sixth lens group is the second focus group.

25. A zoom lens having, arranged in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, and multiple subsequent lens groups, wherein the spacing between adjacent lens groups changes during zooming, wherein the first lens group does not move during zooming and the second lens group moves during zooming, and the multiple subsequent lens groups include a first focus group and a second focus group located closer to the image than the first focus group, which move during zooming and focusing, respectively, and wherein the zoom lens satisfies the condition: 0.80≦|Mfc2 / Mfc1|≦8.00, where Mfc1 is the amount of movement of the first focus group during focusing from infinity to the closest point at the telephoto end, and Mfc2 is the amount of movement of the second focus group during focusing from infinity to the closest point at the telephoto end.

26. An imaging device comprising: a zoom lens according to any one of claims 1 to 25; and an imaging element for capturing an image of a subject through said zoom lens.

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